The official recommendations to sailors is: Shut off the engine, take down the sails, make no sound, wait.
What sailors will admit they do but not tell anyone: Dump a bit of diesel or petrol in the water around the boat to scare away the orcas.
There are also some new gadgets available to make high pitched sounds that humans can't hear but scare away orcas (and dolphins, unfortunately) but no idea if they work well.
What sailors will admit they do but not tell anyone: Dump a bit of diesel or petrol in the water around the boat to scare away the orcas.
There are also some new gadgets available to make high pitched sounds that humans can't hear but scare away orcas (and dolphins, unfortunately) but no idea if they work well.